So, what happens to the lost hours? How does the data collector figure out uploads or downloads when it was not running for several hours? My biggest worry is I had some multiple day (5+) that uploaded and reported while the data collector was not working and those hours will get purged/lost.

Same here, but it only started on the tasks returned 30 minutes ago for me.

The server status page currently shows 102 tasks ready to send, a 1 hour transitioner backlog and 400 workunits in the validation queue. The validation queue has increased by 83 in the last 10 minutes, so there's definitely something wrong at the moment.

The last tasks returned by my computers have status Completed, waiting for validation and the scheduler replies include the line:

<message priority="low">Project has no tasks available</message>

Edit: New tasks were received as I was making the post, computers had no WUProp work for 33 and 34 minutes. The validation queue is now up to 623.
____________"The ultimate test of a moral society is the kind of world that it leaves to its children." - Dietrich Bonhoeffer